Increased costs relating to fossil fuel consumption, including energy, environmental and other costs, have resulted in significant consumer, industrial and government demand for more efficient and less fossil fuel-dependent systems. Significant research and development resources are presently directed towards power sources and electric energy storage devices, such as batteries, ultra-capacitors, solar panels, fuel-cells, etc. Each of these devices typically supplies a DC power signal at a particular voltage level, which must be converted to other DC levels for use with some devices, or inverted into an AC signal to couple to an AC power grid or to supply a power signal to an AC electric motor.
Similarly, it can be desirable to convert a single or three phase AC power signal into a DC power signal, for example, to allow the electric energy in the signal to be stored or transmitted to another DC electrical system.
Existing switching devices typically contain a relatively high number of switches and other components, making them inefficient due to increased power loss, heat dissipation, and production costs. For example, some tie-grid inverters that are used to couple a DC power signal to an AC power grid employ isolating transformers as well as a multistage conversion process, which converts DC power to high frequency AC, back to DC, then to a final AC output voltage. Multi-stage converters typically require an energy storage element to decouple converter inputs and outputs. In electrified traction systems, the use of different DC sources operating at different voltage levels requires the use of DC to DC converters to adjust voltage levels.
There is a need for more efficient power converters.